In the past, to make moulded hams, moulds were used which were filled with pieces of meat, dried, pressed and then finally cooked. These moulds have been modernized by making them into the shape of relatively long troughs, assembling these troughs parallel to one another in rigid frames (which generally require the use of forklifts for handling), stacking these frames to form blocks, placing the blocks into enclosed areas, and then cooking and cooling the meat by circulating a heat transfer fluid for the cooking and a coolant fluid for cooling. The cooking operation ends when the block is removed from the enclosed area, unstacked and the hams removed from the moulds.
To press the ham into the troughs, the bases thereof are connected to covers and spring systems which are used to press the ham contents into the troughs situated immediately below them in the stack.
European patents BP-A-0 292 417 and BP-A-0 638 270 concern stackable moulds of the aforementioned type. In BP-A-0 292 417, a stackable set of moulds is described (see FIGS. 4 and 5), in which each of the troughs has a rectangular cross-section. Plates suspended under their flat bases serve as covers for the troughs of the moulds immediately below them in the stack. The size of the plates is slightly less than the inside cross-section of the troughs. As well, the vertical distance between a cover and the base of the overhead trough is fixed. At the start of cooking the covers penetrate less into the lower troughs than shown (see FIGS. 4 and 5), During cooking, the covers penetrate further due to the pressure resulting from the weight of the block and tensioning means mounted on the outside of the moulds between horizontal bars used for handling the moulds.
In EP-A-0 638 270, a set of stackable moulds is described in which each of the bases of the troughs press downwardly from above onto the hams contained in the troughs of the mould immediately below the pressing mold in the stack. Moreover, in each trough, a false movable base is provided, above its base, on which the lower part of the ham to be cooked rests. Between the actual base and the false base, elastic means are provided which push the false base upward. Thus, during cooking, the ham is pressed between the actual base of the upper trough and the false base of the lower trough using the weight of the stack, the tensioning means and the elastic means.
The means provided in the above mentioned patents focus on troughs having a rectangular cross-section for moulding hams with a rectangular cross-section. They work well because small movements of the trough do not result in undesirable jammings. Additionally, the elastic means provided in the second patent allows the ham to be pressed during cooking, which translates into a better quality food product.
The moulding and cooking of hams using troughs with a cylindrical cross-section has also been considered in BP-A-0 638 270, noted above (see FIG. 5). The false base, instead of being flat, has the shape of the base of a trough, concave toward the top, with longitudinal sides which drop and ensure a guide within the trough. However, this guiding may not be reliable, for example, if a piece of ham becomes unexpectedly lodged between a longitudinal aide and the lateral wall of the trough.